Print PageThe pace of deforestation worldwide has necessitated the development of strategies that restore forest cover quickly and efficiently. One such strategy is applied nucleation, which involves planting small patches of trees as focal areas for recovery. Once planted, these patches, or nuclei, attract dispersers and facilitate establishment of new woody recruits, expanding the forested area over time. We resampled a reclaimed landfill in New Jersey, USA that was planted in an applied nucleation design in 1991. At that time, sixteen plots were planted with 21 trees and shrubs according to a 2x2 factorial design. The factors were: a) plant size; and b) the inclusion of nitrogen fixing-trees. There were also unplanted control plots. The abundance and species composition of all woody stems in planted and control plots, and areas in between plots, were sampled through 1996, then again in 2010.
Results/Conclusions
In the 19 years since the planting, the site has been largely reforested with wind-dispersed species such as Fraxinus americana (American ash). Relatively few of the original planted trees remain, but the legacy of planting could still be seen: the locations of the original nuclei had over four times as many woody stems above 1.2 m in height (p < 0.001), and had significantly more species. Morus spp. (mulberry), a bird-dispersed tree that was not part of the original planting mixture, was abundant in planted plots but was largely absent in unplanted plots. There were no differences (p> 0.10) in the number of woody stems or the species number between plots planted with large vs. small trees, or between plots that included nitrogen fixers. Though we expected that new species would disperse from nearby habitats over time, all species recorded at the site in 2010 were present in 1996. The absence of nearby seed sources in this highly disturbed region may have influenced recruitment of new species. Our results indicate that applied nucleation can influence both the stem density and species composition of reforesting areas. It can also facilitate the dispersal of some bird-dispersed species that, otherwise, might be slower to recruit than wind-dispersed species.
